Voltage variations

[BOP4ever]

I noticed while driving the bat indication on the scan master dropping to upper 12's low 13's do I went out dnd did some checking. Engine off car had been setting a week or do battery showed 12.25 volts. Cranked it up
And I had 14 at the battery and 14.4 on the alternator stud to ground strap at the back of the engine.
The scan master showed 13 to 13.7 kinda erratic ..,
Is there a problem or is this normal . Scanmaster seemed to steady out after running about 10 minutes at 13 to 13.25 volts.

 

[Nick Micale]

It is not unusual for the Scanmaster to show a volt or so less than voltage at the battery.

One issue is the Scanmaster ground is usually on or in, the dash, not directly back to the battery. Make sure the neg cable ground to the body is clean.

In a DC circuit, it MUST be completed back to the battery, so with your ground going through the body, there is a LOT of resistance getting back to the battery.

Many years ago I learned from Red Armstrong that our turbo cars need to be treated like "electric" car since so much depends on it, unlike the carbed cars we were used to fixing and racing!

 

[BOP4ever]

It struck me odd that before I pulled the engine turbo link would show low voltage always concerned me. It was like 12.4 to 13 tops.
After putting the engine back in and putting the scan master in it was showing 14 now a couple months later I am seeing it start to drop again seems to drop as the car warms up...
Do I need more grounds?